Ethnic Origin of Crime Scene Evidential Materials Determination in Three Main Ethno-linguistic Population Groups in Nigeria

DNA analysis using autosomal short tandem repeat (microsatellite) polymorphism is a useful tool for forensic purposes, such as individual identification, stain analysis and paternity testing. Analyses of such materials are carried out by the comparison of profiles from questioned samples or crime scene with those from suspects or victims or from database. In some instances, the profiles generated will neither match that from suspects nor the database. The objective of the current study is to identify population specific markers that will show distinct genetic variability among the three main ethno-linguistic population groups in Nigeria. The profiles generated can be used to infer ethnic origin of test samples from the populations in an ethnically blinded test.

Allele frequencies for each ethnic group from 315 unrelated individuals representing the three populations; Ibo, Hausa and Yoruba were generated using 15 Microsatellite loci (STRs) from Applied Biosystems. Multi-locus genotype frequencies were utilized for testing conformity with Hardy-Weinberg equilibrium. Chi-square goodness of fit showed seven loci to be in Hardy-Weinberg equilibrium. However after Bonferoni correction all loci were found to be in conformity with Hardy-Weinberg equilibrium.

The allele frequencies generated for each population were tested in the determination of ethnic origin of twenty test samples randomly collected in an ethnically blinded test. The ethnic origins of the twenty samples were correctly determined with 99.5% success, by using the principle that the ratio of profile frequencies for the same profile in different ethnic groups is a likelihood ratio.